Surface Treated Copper Foil and Laminate Using the Same

ABSTRACT

A surface treated copper foil which is well bonded to a resin and achieves excellent visibility when observed through the resin, and a laminate using the same are provided. A surface treated copper foil comprising at least one surface treated surface with a color difference ΔE*ab of 40 or more based on JIS Z 8730, and a difference between the top average Bt and the bottom average Bb in a brightness curve extending from an end of the copper foil to a portion without the copper foil ΔB (ΔB=Bt−Bb) of 40 or more, after lamination of the surface treated surface to a polyimide having a ΔB (Pl) defined as above of 50 or more and 65 or less before being laminated to the copper foil, wherein the brightness curve is obtained from an observation spot versus brightness graph of measurement results of the brightness of the photographed image of the copper foil through the polyimide with a CCD camera for the respective observation spots along the direction perpendicular to the extending direction of the observed copper foil.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is the United States national phase ofInternational Application No. PCT/JP2013/080478, filed on Nov. 11, 2013.This application claims the benefit and priority of Japanese PatentApplication No. 2012-247916, filed Nov. 9, 2012; Japanese PatentApplication No. 2012-288815, filed on Dec. 28, 2012; and Japanese PatentApplication No. 2013-013710, filed on Jan. 28, 2013. The entiredisclosures of each of the above applications are incorporated herein byreference.

FIELD OF THE INVENTION

The present invention relates to a surface treated copper foil and alaminate using the same.

BACKGROUND OF THE INVENTION

A flexible printed wiring or circuit board (hereinafter referred to asFPC) is employed in a compact electronic apparatus such as a smart phoneand a tablet PC due to the easiness of wiring and the lightness. Due tothe recent improvement of functionality of electronic apparatuses, thesignal transmission rate has been accelerated, so that impedancematching is an important factor even for an FPC. In order to achieveimpedance matching for the increased signal capacity, a resin insulatinglayer (e.g., polyimide) as the base of an FPC has been thickened. Inorder to meet the demand for densification of wirings, multilayering ofan FPC has been further developed. On the other hand, when an FPC isprocessed for bonding to a liquid crystal substrate and mounting an ICchip, alignment is performed with a positioning pattern which isvisually recognized through a resin insulating layer remained afteretching of the copper foil of a laminate composed of the copper foil andthe resin insulating layer. The visibility of the resin insulating layeris therefore important.

A copper clad laminate composed of a laminate of a copper foil and aresin insulating layer may be manufactured from a rolled copper foilhaving a roughened plated surface. The rolled copper foil is usuallymanufactured from tough pitch copper (oxygen content: 100 to 500 ppm byweight) or oxygen-free copper (oxygen content: 10 ppm by weight or less)as a raw material ingot, which is hot rolled and then subjected torepeated cold rolling and annealing to a predetermined thickness.

Examples of the techniques include the followings. Patent Literature 1discloses an invention of a copper clad laminate of a polyimide film anda low profile copper foil, which allows a film after etching of thecopper foil to have a light transmittance of 40% or more at a wavelengthof 600 nm, with a haze value (HAZE) of 30% or less and an adhesivestrength of 500 N/m or more.

Patent Literature 2 discloses an invention of a chip on flexible (COF)flexible printed wiring board having an insulating layer on which aconductive layer of electrolytic copper foil is laminated, allowing theinsulating layer in an etched region after circuit formation by etchingof the conductive layer to have a light transmittance of 50% or more.The electrolytic copper foil includes a rustproof layer of nickel-zincalloy at the joint area bonded to the insulating layer. The joint areahas a surface roughness (Rz) of 0.05 to 1.5 μm and a specular gloss of250 or more at an incident angle of 60°.

Patent Literature 3 discloses an invention of a method for processing acopper foil for a printed circuit, including forming a cobalt-nickelalloy plated layer after surface roughening treatment of the copper foilsurface by plating with a copper-cobalt-nickel alloy, and furtherforming a zinc-nickel alloy plated layer.

PATENT LITERATURE

[Patent Literature 1]

Japanese Patent Laid-Open No. 2004-98659

[Patent Literature 2]

International Publication No. WO 2003/096776

[Patent Literature 3]

Japanese Patent No. 2849059

SUMMARY OF THE INVENTION

In Patent Literature 1, the adhesiveness of a low profile copper foil isimproved by blackening treatment or with an organic treating agent afterplating treatment. The copper foil causes disconnection due to fatiguein some cases for use in need of flexibility of a copper clad laminate,and has poor transparency of a resin in some cases.

In Patent Literature 2, since no roughening treatment is performed, theadhesion strength between a copper foil and a resin is low andinsufficient for use other than as a COF flexible printed wiring board.

Furthermore, in the processing method according to Patent Literature 3,although the refinement treatment of a copper foil is feasible withCu—Co—Ni, excellent visibility cannot be achieved when the copper foilis observed through a resin.

The present invention provides a surface treated copper foil which iswell bonded to a resin and achieves excellent visibility when observedthrough the resin, a laminate using the same.

As a result of earnest research effort, the present inventors found thatthe excellent transparency of a resin can be achieved without influenceof the type and the thickness of a substrate resin film by thefollowing. A copper foil which is controlled to have a surface colordifference in a predetermined range by surface treatment is photographedthrough a polyimide substrate laminated on the treated surface with aCCD camera. A graph of observation spot versus brightness is producedfrom the image. An attention is paid to the gradient of the brightnesscurve drawn in the graph in the vicinity of the end of the copper foilsuch that the gradient of the brightness curve is controlled.

An aspect of the present invention accomplished based on the abovefindings is a surface treated copper foil comprising at least onesurface treated surface with a color difference ΔE*ab of 40 or morebased on JIS Z 8730, and a difference between the top average Bt and thebottom average Bb in a brightness curve extending from an end of thecopper foil to a portion without the copper foil ΔB (ΔB=Bt−Bb) of 40 ormore, after lamination of the surface treated surface to a polyimidehaving a ΔB (Pl) defined as above of 50 or more and 65 or less beforebeing laminated to the copper foil, wherein the brightness curve isobtained from an observation spot versus brightness graph of measurementresults of the brightness of the photographed image of the copper foilthrough the polyimide with a CCD camera for the respective observationspots along the direction perpendicular to the extending direction ofthe observed copper foil.

In another embodiment of the surface treated copper foil of the presentinvention, an Sv defined by the following expression (1) is 3.0 or more:

Sv=(ΔB×0.1)/(t1−t2)(1);

wherein t1 represents a value pointing the position of the intersectionclosest to the copper foil among the intersections of the brightnesscurve and Bt in the observation spot versus brightness graph, and t2represents a value pointing the position of the intersection closest tothe copper foil among the intersections of the brightness curve and0.1ΔB in the range from the intersections of the brightness curve and Btto a depth of 0.1ΔB with Bt as reference.

In further another embodiment of the surface treated copper foil of thepresent invention, the surface of the surface treated copper foil has acolor difference ΔE*ab of 43 or more.

In further another embodiment of the surface treated copper foil of thepresent invention, the Sv defined by the expression (1) in thebrightness curve is 3.5 or more.

In further another embodiment of the surface treated copper foil of thepresent invention, the Sv defined by the expression (1) in thebrightness curve is 3.9 or more.

In further another embodiment of the surface treated copper foil of thepresent invention, the Sv defined by the expression (1) in thebrightness curve is 5.0 or more.

In further another embodiment of the surface treated copper foil of thepresent invention, the surface has a TD average roughness Rz of 0.20 to0.64 μm, and the copper foil surface has a three-dimensional surfacearea A to two-dimensional surface area B ratio A/B of 1.0 to 1.7.

In further another embodiment of the surface treated copper foil of thepresent invention, the surface has a TD average roughness Rz of 0.26 to0.62 μm.

In further another embodiment of the surface treated copper foil of thepresent invention, the A/B is 1.0 to 1.6.

Further another aspect of the present invention is a laminate includinga lamination of the surface treated copper foil of the present inventionand a resin substrate.

Further another aspect of the present invention is a printed wiringboard comprising the surface treated copper foil of the presentinvention.

Further another aspect of the present invention is an electronicapparatus comprising the printed wiring board of the present invention.

Further another aspect of the present invention is a method formanufacturing a printed wiring board having two or more connectedprinted wiring boards comprising connecting two or more of the printedwiring boards of the present invention.

Further another aspect of the present invention is a method formanufacturing a printed wiring board having two or more connectedprinted wiring boards comprising the step of connecting at least oneprinted wiring board of the present invention to another printed wiringboard of the present invention or to a printed wiring board other thanthe printed wiring board of the present invention.

Further another aspect of the present invention is an electronicapparatus comprising at least one printed wiring board connected to atleast one printed wiring board of the present invention.

Further another aspect of the present invention is a method formanufacturing a printed wiring board including at least the step ofconnecting a printed wiring board of the present invention and acomponent.

Further another aspect of the present invention is a method formanufacturing a printed wiring board having two or more connectedprinted wiring boards including at least the step of connecting at leastone printed wiring board of the present invention to another printedwiring board of the present invention or to a printed wiring board otherthan the printed wiring board of the present invention, and the step ofconnecting a printed wiring board of the present invention or a printedwiring board having two or more connected printed wiring boards of thepresent invention to a component.

According to the present invention, a surface treated copper foil whichis well bonded to a resin and achieves excellent visibility whenobserved through the resin, a laminate using the same can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram for defining Bt and Bb.

FIG. 2 is a schematic diagram for defining t1, t2, and Sv.

FIG. 3 is a schematic diagram illustrating the constitution of aphotographic device and a method for measuring the gradient of abrightness curve for evaluation of the gradient of the brightness curve.

FIG. 4 a is a SEM observation photograph of the copper foil surface inComparative Example 1 for evaluating Rz.

FIG. 4 b is a SEM observation photograph of the copper foil surface inExample 1 for evaluating Rz.

FIG. 5 is a photograph of the external appearance of dirt for use in anExample.

FIG. 6 is a photograph of the external appearance of dirt for use in anExample.

DETAILED DESCRIPTION OF THE INVENTION Aspect of Surface Treated CopperFoil and Manufacturing Method Thereof

A copper foil for use in the present invention is effectively used for acopper foil which is laminated on a resin substrate so as to produce alaminate which is then etched to form a circuit.

The copper foil for use in the present invention may be any one of anelectrolyte copper foil and a rolled copper foil. The joint area of acopper foil to be bonded to a resin substrate, i.e., the surface treatedsurface, may be usually subject to a roughening treatment byelectrodeposition for forming a knotty copper foil surface afterdegreasing, in order to improve the peel strength of the copper foilafter lamination. Although an electrolyte copper foil has irregularitieswhen manufactured, the irregularities can be further enlarged withroughening treatment for enhancing the projection portion of theelectrolyte copper foil. In the present invention, the rougheningtreatment can be performed by alloy plating such as copper-cobalt-nickelalloy plating and copper-nickel-phosphorus alloy plating, preferably bycopper alloy plating. Common copper plating or the like may be performedas a pre-treatment before roughening in some cases, and common copperplating or the like may be also performed as a finishing treatment afterroughening so as to prevent the detachment of an electrodepositedmaterial in some cases.

The surface of a copper foil for use in the present invention may beprovided with a heat-resistant plating layer or a rustproof platinglayer, after a roughening treatment or without a roughening treatment. Aplating treatment with a Ni—W plating bath under the followingconditions may be employed as a surface treatment for applying theheat-resistant plating layer or a rustproof plating layer to the surfacewithout a roughening treatment:

Plating bath composition: Ni: 20 to 30 g/L, and W: 15 to 40 mg/L;

pH: 3.0 to 4.0;

Temperature: 35 to 45° C.;

Current density D_(k): 1.7 to 2.3 A/dm²; and

Plating time: 18 to 25 sec.

The thickness of a copper foil for use in the present invention is notspecifically limited, including, for example, 1 μm or more, 2 μm ormore, 3 μm or more, 5 μm or more, and, for example, 3,000 μm or less,1,500 μm or less, 800 μm or less, 300 μm or less, 150 μm or less, 100 μmor less, 70 μm or less, 50 μm or less, and 40 μm or less.

Examples of the rolled copper foil of the present invention include acopper alloy foil which contains at least one element such as Ag, Sn,In, Ti, Zn, Zr, Fe, P, Ni, Si, Te, Cr, Nb, V, B, and Co. With highconcentration of the elements (e.g., 10 mass % or more in total), theconductivity may be reduced in some cases. The conductivity of a rolledcopper foil is preferably 50% IACS or more, more preferably 60% IACS ormore, further preferably 80% IACS or more. Examples of the rolled copperfoil include a copper foil made from tough pitch copper (JIS H 3100 C1100) and oxygen free copper (JIS H 3100 C 1020).

The manufacturing conditions of an electrolyte copper foil that can beused in the invention of the present application are shown in thefollowing.

<Electrolyte Composition>

Copper: 90 to 110 g/L;

Sulfuric acid: 90 to 110 g/L;

Chlorine: 50 to 100 ppm;

Leveling agent 1 (bis(3-sulfopropyl)disulfide): 10 to 30 ppm; and

Leveling agent 2 (amine compound): 10 to 30 ppm.

The amine compound represented by the following formula may be used asthe above-mentioned amine compound.

(In the chemical formula, R₁ and R₂ are selected from the groupconsisting of a hydroxyalkyl group, an ether group, an aryl group, anaromatic substituted alkyl group, an unsaturated hydrocarbon group, andan alkyl group.)

<Manufacturing Conditions>

Current density: 70 to 100 A/dm²;

Electrolyte temperature: 50 to 60° C.;

Linear velocity of electrolyte: 3 to 5 m/sec; and

Electrolysis time: 0.5 to 10 min.

In copper-cobalt-nickel alloy plating as roughening treatment,electroplating may be performed such that a ternary alloy layer withdeposition amounts of copper of 15 to 40 mg/dm², cobalt of 100 to 3,000μg/dm², and nickel of 100 to 1,500 μg/dm² is formed. A deposition amountof Co less than 100 μg/dm² may cause degradation of heat resistance andetching properties in some cases. A deposition amount of Co more than3,000 μg/dm² is not suitable in the case that effects of magneticproperties have to be considered, causing etching stains with reducedacid resistance and chemical resistance in some cases. A depositionamount of Ni less than 100 μg/dm² may cause degradation of heatresistance. On the other hand, a deposition amount of Ni more than 1,500μg/dm² may increase the amount of etching residue in some cases. Thepreferable deposition amount of Co is 1,000 to 2,500 μg/dm², and thepreferable deposition amount of Nickel is 500 to 1,200 μg/dm². In thespecification, the presence of etching stains means that Co remainsundissolved in etching with copper chloride, and the presence of etchingresidue means that Ni remains undissolved in alkali etching withammonium chloride.

The plating bath and the plating conditions for forming the ternarycopper-cobalt-nickel alloy plating are as follows:

Plating bath composition: Cu: 10 to 20 g/L, Co: 1 to 10 g/L, and Ni: 1to 10 g/L;

pH: 1 to 4;

Temperature: 30 to 50° C.;

Current density D_(k): 20 to 30 A/dm²; and

Plating time: 1 to 5 sec.

The conditions for copper-nickel-phosphorus alloy plating as rougheningtreatment of the present invention are as follows:

Plating bath composition: Cu: 10 to 50 g/L, Ni: 3 to 20 g/L, and P: 1 to10 g/L;

pH: 1 to 4;

Temperature: 30 to 40° C.;

Current density D_(k): 20 to 50 A/dm²; and

Plating time: 0.5 to 3 sec

The conditions for copper-nickel-cobalt-tungsten alloy plating asroughening treatment of the present invention are as follows:

Plating bath composition: Cu: 5 to 20 g/L, Ni: 5 to 20 g/L, Co: 5 to 20g/L, and

W: 1 to 10 g/L;

pH: 1 to 5;

Temperature: 30 to 50° C.;

Current density D_(k): 20 to 50 A/dm²; and

Plating time: 0.5 to 5 sec.

The conditions for copper-nickel-molybdenum-phosphorus alloy plating asroughening treatment of the present invention are as follows:

Plating bath composition: Cu: 5 to 20 g/L, Ni: 5 to 20 g/L, Mo: 1 to 10g/L, and P: 1 to 10 g/L;

pH: 1 to 5;

Temperature: 20 to 50° C.;

Current density D_(k): 20 to 50 A/dm²; and

Plating time: 0.5 to 5 sec.

After the roughening treatment, a cobalt-nickel alloy plating layerhaving deposition amounts of cobalt of 200 to 3,000 μg/dm² and nickel of100 to 700 μg/dm² on the roughened surface may be formed. This treatmentcan be regarded as a kind of rustproof treatment in a broad sense. Thecobalt-nickel alloy plating layer needs to be formed to an extent not tosubstantially reduce the adhesion strength between the copper foil andthe substrate. A deposition amount of cobalt less than 200 μg/dm² maycause reduction of heat resistant peel strength with degraded oxidationresistance and chemical resistance in some cases. In addition, anotherreason that a small amount of cobalt is not preferred is that thetreated surface has a reddish color. A deposition amount of cobalt morethan 3,000 μg/dm² is not suitable in the case that effects of magneticproperties have to be considered, causing etching stains with reducedacid resistance and chemical resistance in some cases. The preferabledeposition amount of cobalt is 500 to 2,500 μg/dm². On the other hand, adeposition amount of nickel less than 100 μg/dm² may cause reduction ofheat resistant peel strength with degraded oxidation resistance andchemical resistance in some cases. An amount of nickel more than 1,300μg/dm² results in poor alkali etching properties. The preferabledeposition amount of nickel is 200 to 1,200 μg/dm².

The conditions for cobalt-nickel alloy plating are as follows:

Plating bath composition: Co: 1 to 20 g/L and Ni: 1 to 20 g/L;

pH: 1.5 to 3.5;

Temperature: 30 to 80° C.;

Current density D_(k): 1.0 to 20.0 A/dm²; and

Plating time: 0.5 to 4 sec.

According to the present invention, a zinc plating layer with adeposition amount of 30 to 250 μg/dm² is further formed on acobalt-nickel alloy plating layer. A deposition amount of zinc less than30 μg/dm² may eliminate the effect for improving the degradation rate ofheat resistance in some cases. On the other hand, a deposition amount ofzinc more than 250 μg/dm² may drastically worsen the degradation rate ofhydrochloric acid resistance in some cases. The deposition amount ofzinc is preferably 30 to 240 μg/dm², more preferably 80 to 220 μg/dm².

The conditions for the zinc plating are as follows:

Plating bath composition: Zn: 100 to 300 g/L;

pH: 3 to 4;

Temperature: 50 to 60° C.;

Current density D_(k): 0.1 to 0.5 A/dm²; and

Plating time: 1 to 3 sec.

Alternatively, a plating layer of zinc alloy such as that of zinc-nickelalloy may be formed instead of the zinc plating layer. On the outermostsurface, a rustproof layer may be further formed by treatment such aschromating or application of a silane coupling agent.

Burnt plating in an aqueous solution of copper sulfate is a conventionaltechnique usually employed for roughening the surface of a copper foil.Alloy plating with a plating bath including a metal other than coppersuch as copper-cobalt-nickel alloy plating and copper-nickel-phosphorusalloy plating is a surface treatment which allows a copper foil surfaceto have a color difference ΔE*ab of 40 or more based on JIS Z 8730.

(Surface Color Difference ΔE*ab)

The surface treated copper foil of the present invention has at leastone surface of which color difference ΔE*ab is controlled to be 40 ormore based on JIS Z 8730. This configuration allows for clear contrastto the back surface, improving the visibility of the copper foilobserved through the polyimide substrate. As a result, use of the copperfoil in forming a circuit allows for easy alignment of an IC chip to bemounted with a positioning pattern which is visually recognized throughthe polyimide resin. In the case that the color difference ΔE*ab of acopper foil surface is less than 40, unclear contrast to the backsurface may be caused. The color difference ΔE*ab of a copper foilsurface is more preferably 43 or more, further preferably 50 or more.

In the specification, the color difference ΔE*ab of a copper foilsurface is measured by a color difference meter, and represented by thefollowing expression as a comprehensive index indicated by using theL*a*b colorimetric system based on JIS Z 8730 regardingblack/white/red/green/yellow/blue colors, with ΔL: white and black, Δa:red and green, and Δb: yellow and blue.

ΔE*ab=√{square root over (ΔL ² +Δa ² +Δb ²)}  [Expression 1]

(Average Roughness Rz of Copper Foil Surface)

The surface treated copper foil of the present invention may be anon-roughening treated copper foil or a roughening treated copper foilhaving roughened grains. The roughening treated surface has a TD averageroughness Rz of preferably 0.20 to 0.64 μm. Such a configuration allowsfor good adhesion to a resin with increased peel strength, improving thetransparency of the resin after removal of the copper foil by etching.Consequently alignment of an IC chip to be mounted with a positioningpattern which is visually recognized through the resin can be easilyperformed. A TD average roughness Rz less than 0.20 μm may result in aninsufficient roughening treatment of the copper foil surface, which maycause a problem of insufficient adhesion to the resin. On the otherhand, a TD average roughness Rz more than 0.64 μm may allowirregularities of the resin surface to be enlarged after removal of thecopper foil by etching, which may cause a problem of defect intransparency of the resin. The TD average roughness Rz of a treatedsurface is more preferably 0.26 to 0.62 μm, further preferably 0.40 to0.55 μm.

In order to achieve the visibility effect, the TD surface roughness (Rz)and the glossiness on the treatment side of a copper foil are controlledbefore the surface treatment. Specifically, the TD surface roughness(Rz) of the copper foil is controlled to be 0.20 to 0.55 μm, preferably0.20 to 0.42 μm, before the surface treatment. Such a copper foil can bemade by rolling with adjustment of the oil film equivalent of a rollingoil (high gloss rolling) or by rolling with adjustment of the surfaceroughness of a rolling roll (For example, in measurement in thedirection perpendicular to the circumferential direction of a roll, thearithmetic average roughness Ra (JIS B 0601) of the rolling roll surfacecan be controlled to be 0.01 to 0.25 μm. In the case of large arithmeticaverage roughness Ra of a rolling roll surface, the copper foil isinclined to have a large TD roughness (Rz) with a lower glossiness. Inthe case of small arithmetic average roughness Ra of a rolling rollsurface, the copper foil is inclined to have a small TD roughness (Rz)with a higher glossiness). Alternatively such a copper foil can be madeby chemical polishing such as chemical etching, or electrolyticpolishing in a phosphoric acid solution. Since the TD surface roughness(Rz) and the glossiness of a copper foil are thus controlled to be inthe range before the surface treatment, the surface roughness (Rz) andthe surface area of the copper foil after the treatment can be easilycontrolled.

The copper foil before the surface treatment has preferably a TDglossiness of 300 to 910% at 60 degrees, more preferably 500 to 810%,even more preferably 500 to 710%. In the case that a copper foil has anMD glossiness at 60 degrees less than 300% before the surface treatment,more defects in transparency of the resin may be caused compared withthe case of 300% or more. In the case of more than 910%, a problem ofdifficulty in manufacturing may be caused.

The high gloss rolling may be performed with an oil film equivalentdefined by the following expression of 13,000 to 24,000 or less:

Oil film equivalent={(rolling oil viscosity[cSt])×(sheet passagerate[mpm]+roll circumferential rate[mpm])}/{(roll bitingangle[rad])×(material yield stress[kg/mm²])}

The rolling oil viscosity [cSt] is kinetic viscosity at 40° C.

In order to control the oil film equivalent to be 13,000 to 24,000, aknown method may be used such as use of a low-viscosity rolling oil orslowing down of sheet passage rate.

Chemical polishing is performed with an etching solution of sulfuricacid-hydrogen peroxide-water or ammonia-hydrogen peroxide-water with aconcentration lower than normal, for an extended period of time.

(Brightness Curve)

A polyimide having a ΔB (Pl), which is defined in the following, of 50or more and 65 or less before being laminated to a copper foil islaminated on the surface treated surface of the surface treated copperfoil of the present invention. The copper foil is then photographedthrough the polyimide with a CCD camera. The brightness of thephotographed image is measured for the respective observation spotsalong the direction perpendicular to the extending direction of theobserved copper foil, so that an observation spot versus brightnessgraph is made. The brightness curve extending from an end of the copperfoil to a portion without the copper foil has top average Bt and bottomaverage Bb, with difference ΔB (ΔB=Bt−Bb). The surface treated copperfoil of the present invention has a ΔB of 40 or more.

In the observation spot versus brightness graph, Sv defined by thefollowing expression (1) is preferably 3.0 or more, wherein t1represents a value pointing the position of the intersection closest tothe copper foil among the intersections of the brightness curve and Bt,and t2 represents a value pointing the position of the intersectionclosest to the copper foil among the intersections of the brightnesscurve and 0.1ΔB in the range from the intersections of the brightnesscurve and Bt to a depth of 0.1ΔB with Bt as reference:

Sv=(ΔB×0.1)/(t1−t2)  (1)

With reference to drawing, “top average Bt of brightness curve,” “bottomaverage Bb of brightness curve,” and the following “t1,” “t2,” and “Sv”are described below.

In FIG. 1( a) and FIG. 1( b), schematic diagrams for defining Bt and Bbare shown for a copper foil having a width of approximately 0.3 mm. Inthe case of a copper foil having a width of approximately 0.3 mm, thebrightness curve may be in a V-shape as shown in FIG. 1( a), or may bein a bottomed shape as shown in FIG. 1( b). In both instances, “topaverage Bt of brightness curve” represents the average of brightnessmeasured at 5 spots at intervals of 30 μm from a position 50 μm awayfrom the end position of both sides of a copper foil (total 10 spots onboth sides). On the other hand, “bottom average Bb of brightness curve”represents the lowest value of the brightness at the tip of the V-shapedvalley for the brightness curve in a V-shape as shown in FIG. 1( a), andthe value of the central part of the approximately 0.3 mm-width for thebrightness curve in a bottomed shape as shown in FIG. 1( b). A mark mayhave a width of about 0.2 mm, 0.16 mm, or 0.1 mm. Alternatively, “topaverage Bt of brightness curve” may represent the average of brightnessmeasured at 5 spots at intervals of 30 μm from a position 100 μm away, aposition 300 μm away, or a position 500 μm away from the end position ofboth sides of the mark (total 10 spots on both sides).

In FIG. 2, a schematic diagram for defining t1, t2, and Sv is shown. Theterm “t1 (pixel×0.1)” represents the intersection closest to the copperfoil among the intersections of the brightness curve and Bt. The term“t2 (pixel×0.1)” represents the intersection closest to the copper foilamong the intersections of the brightness curve and 0.1ΔB in the rangefrom the intersections of the brightness curve and Bt to a depth of0.1ΔB with Bt as reference. On this occasion, the gradient of thebrightness curve represented by the line connecting t1 and t2 is definedby Sv (gradation/pixel×0.1) calculated from 0.1ΔB in y-axis directionand (t1−t2) in x-axis direction. One pixel in the transverse axiscorresponds to a length of 10 μm. Sv represents the smaller valueobtained by measurement on both sides of a copper foil. In the case thata plurality of “intersections of the brightness curve and Bt” arepresent due to instability of the shape of the brightness curve, theintersection closest to the copper foil is employed.

In the image photographed by a CCD camera, a portion having no copperfoil has high brightness, while the brightness sharply falls down at theend of a copper foil. With good visibility through the polyimidesubstrate, the falling state of brightness can be clearly observed. Onthe other hand, with poor visibility through the polyimide substrate,the brightness does not drastically fall down from “high” to “low” atthe vicinity of the end of a copper foil, so that the gradual fallingstate results in the unclear falling state of brightness.

Based on such findings, a polyimide having a ΔB (Pl), which is definedin the following, of 50 or more and 65 or less before being laminated toa copper foil is laminated on the surface treated surface. The copperfoil is then photographed through the polyimide with a CCD camera. Thebrightness of the photographed image is measured for the respectiveobservation spots along the direction perpendicular to the extendingdirection of the observed copper foil, so that an observation spotversus brightness graph is made. The brightness curve extending from anend of the copper foil to a portion without the copper foil has topaverage Bt and bottom average Bb, with difference ΔB (ΔB=Bt−Bb). Thesurface treated copper foil of the present invention has a ΔB of 40 ormore. Such a configuration allows the discrimination of a copper foilthrough polyimide with a CCD camera to be improved without influence ofthe type and the thickness of a substrate resin. Excellent visibility isthus achieved when observation is made through the polyimide resin.Consequently positioning accuracy in copper foil marking or the like isimproved in a predetermined processing of a polyimide substrate in astep for manufacturing an electronic substrate or the like. The effectssuch as improved yields are thus obtained.

The surface of the surface treated copper foil has a color differenceΔE*ab of preferably 43 or more, more preferably 45 or more, morepreferably 50 or more, more preferably 55 or more, more preferably 60 ormore. It is not needed to specify the upper limit of the colordifference ΔE*ab, which may be, for example, 90 or less, 88 or less, 87or less, 85 or less, 75 or less, or 70 or less. Sv is preferably 3.5 ormore, more preferably 3.9 or more, more preferably 4.5 or more, morepreferably 5.0 or more, and more preferably 5.5 or more. Although it isnot needed to specify the upper limit of Sv, which may be, for example,15 or less, or 10 or less. Such a configuration allows for a clearerboundary between a copper foil and a portion other than a copper foil,improving positioning accuracy with less error in copper foil imagerecognition. More accurate alignment is thus achieved.

Meanwhile, after lamination of surface treated copper foils on bothsurfaces of a polyimide, both of the surface copper foils may be removedby etching so as to form a copper foil in a circuit form on one surfaceonly. In the case that excellent visibility of the copper foil in acircuit form is achieved by the observation through the polyimide, sucha surface treated copper foil has excellent visibility by theobservation through a polyimide after lamination to a polyimide.

(Area Ratio)

The ratio A/B of the three dimensional surface area A on the side of thesurface treated surface of a copper foil to the two dimensional surfacearea B greatly affects the transparency of the above-mentioned resin.Namely, for the same surface roughness Rz, the smaller the ratio A/B ofa copper foil, the better transparency of the resin is achieved.Consequently, the ratio A/B of the surface treated copper foil of thepresent invention is preferably 1.0 to 1.7, more preferably 1.0 to 1.6.In the specification, the ratio A/B of the three dimensional surfacearea A of roughened grains on the side of the surface treated surface tothe two dimensional surface area B can be, for example, in the case ofroughening treated surface, the ratio A/B of the surface area A ofroughened particles to the area B of the copper foil shown in the planview from the copper foil surface side.

The surface state such as the morphology and the packing density ofgrains is determined by control of the current density and plating timeduring surface treatment such as particle formation, so that the surfaceroughness Rz, the glossiness, and the area ratio A/B of a copper foilsurface can be controlled.

The surface treated copper foil of the present invention can belaminated to a resin substrate from the surface treated side so as tomanufacture a laminate. The resin substrate is not specifically limitedso long as having characteristics applicable to a printed wiring boardor the like. For example, a paper base phenolic resin, a paper baseepoxy resin, a synthetic fiber fabric base epoxy resin, a glass fabricand paper composite base epoxy resin, a glass fabric and glass nonwovenfabric composite base epoxy resin, or a glass fabric base epoxy resincan be used for a rigid PWB, while a polyester film, a polyimide film, aliquid crystal polymer (LCP) film, or a TEFLON (registered trademark)film can be used for an FPC.

In the lamination method for a rigid PWB, a prepreg is prepared byimpregnating a substrate such as glass fabric with a resin and curingthe resin into a semi-cured state. A copper foil is superimposed on theprepreg so as to be hot pressed from the side opposite to the coatinglayer. A laminate for an FPC can be manufactured by laminating andbonding a copper foil to a substrate such as a polyimide film through anadhesive or without an adhesive under high temperature and highpressure, or by the steps of applying, drying, and curing a polyimideprecursor.

The thickness of a polyimide substrate resin is not specificallylimited. For example, the thickness may be typically 25 μm or 50 μm.

The laminate of the present invention can be used for various kinds ofprinted wiring boards (PWB), and the use is not specifically limited.For example, in the view of the number of layers with a conductorpattern, the laminate can be used for a single-sided PWB, a double-sidedPWB, and a multi-layer PWB (3-layer or more). In the view of the type ofinsulating substrate material, the laminate can be used for a rigid PWB,a flexible PWB (FPC), and a rigid flex PWB. An electronic apparatus ofthe present invention can be formed with such a printed wiring board.(Laminate and positioning method of printed wiring board using thelaminate)

The positioning method of a laminate of a surface treated copper foiland a resin substrate of the present invention is described below.First, a laminate of a surface treated copper foil and a resin substrateis prepared. Specific examples of the laminate of a surface treatedcopper foil and a resin substrate of the present invention include alaminate for an electronic apparatus including a main body substrate, anauxiliary circuit substrate, and a flexible printed substrate forelectrically connecting the above-mentioned substrates, formed of aresin substrate such as polyimide of which at least one surface isprovided with a copper wiring. The flexible printed substrate isaccurately positioned so as to be pressure bonded to the wiringterminals of the main body substrate and the auxiliary circuitsubstrate. In this case, the laminate is composed of a flexible printedsubstrate and a main body substrate of which wiring terminals arepressure bonded for lamination, or composed of a flexible printedsubstrate and a circuit substrate of which wiring terminals are pressurebonded for lamination. The laminate includes a mark formed of a part ofthe copper wiring or another material. The position of the mark is notspecifically limited so long as the position allows for photographingwith photographing means such as a CCD camera through the resin forconstituting the laminate.

The position of the mark is well detected by photographing the mark ofthe laminate thus prepared with photographing means through the resin.Based on the position of the mark thus detected, the laminate of asurface treated copper foil and a resin substrate can be wellpositioned. In the case of using a printed wiring board as a laminate,photographing means well detects the position of the mark by the samepositioning method, allowing for more accurate positioning of theprinted wiring board.

Consequently, use of a printed wiring board having the copper foilaccording to the embodiment of the present invention allows for moreaccurate positioning of the printed wiring board. Consequently defectsin connection are decreased when a printed wiring board is connected toanother printed wiring board, so that yield can be increased. Examplesof the method for connecting a printed wiring board to another printedwiring board include known connecting method such as soldering,connection through an anisotropic conductive film (ACF), connectionthrough an anisotropic conductive paste (ACP), and connection through aconductive adhesive. In the present invention, “a printed wiring board”includes a printed wiring board mounted with components, a printedcircuit board, and a printed board. Two or more printed wiring boards ofthe present invention can be connected so that a printed wiring boardincluding two or more printed wiring boards connected to each other canbe manufactured. At least one printed wiring board of the presentinvention and another printed wiring board of the present invention or aprinted wiring board other than the printed wiring board of the presentinvention can be connected to each other. An electronic apparatus may bemanufactured using such a printed wiring board. In the presentinvention, “a copper circuit” includes a copper wiring. In manufacturingof a printed wiring board, a printed wiring board of the presentinvention may be connected to a component. In manufacturing of a printedwiring board having two or more connected printed wiring boards, atleast one printed wiring board of the present invention may be connectedto another printed wiring board of the present invention or a printedwiring board other than the printed wiring board of the presentinvention, and a printed wiring board having two or more printed wiringboards of the present invention may be connected to a component. In thespecification, examples of the “component” include a connector, a liquidcrystal display (LCD), an electronic component such as a glass substratefor use in an LCD, an electronic component (e.g. an IC chip, an LSIchip, a VLSI chip, and an ULSI chip) including a semiconductorintegrated circuit such as an integrated circuit (IC), a large scaleintegrated circuit (LSI), a very large scale integrated circuit (VLSI),and an ultra-large scale integrated circuit (ULSI), a component forshielding an electronic circuit, and a component for fixing a cover orthe like to a printed wiring board.

The positioning method according to an embodiment of the presentinvention may include a step of transferring a laminate (including alaminate of a copper foil and a resin substrate and a printed wiringboard). In the step of transferring, transferring may be performed, forexample, with a conveyor such as a belt conveyor and a chain conveyor,with a transferring device having an arm mechanism, with a transferringdevice or transferring means for transferring a laminate floated by agas, with a transferring device or transferring means for transferring alaminate through rotation of approximately cylindrical matters(including rollers and bearings), with a transferring device ortransferring means having a hydraulic power source, with a transferringdevice or transferring means having a pneumatic power source, with atransferring device or transferring means having a motor power source,or with a transferring device or transferring means having a stage suchas a gantry moving type linear guide stage, a gantry moving type airguide stage, a stack type linear guide stage, and a linear motor drivenstage. Alternatively the transferring step may be performed with knowntransferring means.

The positioning method according to an embodiment of the presentinvention may be used in a surface mounting machine and a chip mounter.

The laminate of a surface treated copper foil and a resin substrate tobe positioned in the present invention may be a printed wiring boardhaving a resin board and a circuit arranged on the resin board. In thiscase, the mark may be the above-mentioned circuit.

In the present invention, “positioning” includes “detecting the positionof a mark or an object.” In the present invention, “alignment” includes“transferring the mark or the object to a predetermined position on thebasis of the detected position after detection of the position of themark or the object.”

In measuring the Sv value of a printed wiring board, the circuit on theprinted wiring board may be used as a mark to be photographed with a CCDcamera through the resin, instead of a printed mark. In measuring the Svvalue of a copper clad laminate, linearly etched copper may be used as amark to be photographed with a CCD camera through the resin, instead ofa printed mark.

Examples

In Examples 1 to 9 and Comparative Examples 1 to 4, a copper foil wasprepared for each. Each one surface was subject to a plating treatmentas roughening treatment under the conditions described in Table 2 andTable 3.

A rolled copper foil was manufactured as follows. A prescribed copperingot was manufactured to be hot rolled. Subsequently, annealing in acontinuous annealing line at 300 to 800° C. and cold rolling wererepeated such that a rolled sheet with a thickness of 1 to 2 mm wasproduced. The rolled sheet was annealed in a continuous annealing lineat 300 to 800° C. so as to be recrystallized and finally cold rolledinto a copper foil having a thickness described in Table 1. In Table 1,“tough pitch copper” represents a tough pitch copper in accordance withthe standard JIS H 3100 C 1100. In Table 1, “oxygen-free copper”represents an oxygen-free copper in accordance with the standard JIS H3100 C 1020. In Table 1, “ppm” of additive element represents mass ppm.

An electrolyte copper foil was made under the following conditions:

Electrolyte composition (copper: 100 g/L, sulfuric acid: 100 g/L,chlorine: 50 ppm, leveling agent 1 (bis(3-sulfopropyl)disulfide): 10 to30 ppm; and leveling agent 2 (amine compound): 10 to 30 ppm);

Electrolyte temperature: 50 to 60° C.;

Current density: 70 to 100 A/dm²;

Electrolysis time: 1 min; and

Linear velocity of electrolyte: 4 m/sec.

The amine compound represented by the following formula was used as theabove-mentioned amine compound.

(In the chemical formula, R₁ and R₂ are selected from the groupconsisting of a hydroxyalkyl group, an ether group, an aryl group, anaromatic substituted alkyl group, an unsaturated hydrocarbon group, andan alkyl group.)

In Table 1, the key spots in the step of manufacturing a copper foilbefore surface treatment are described. “High gloss rolling” means thatthe final cold rolling (cold rolling after final recrystallizationannealing) was performed at the described oil film equivalent.

Various evaluations of each sample thus made in Examples and ComparativeExamples were performed as follows.

(1) Measurement of Surface Roughness (Rz)

With regard to the surface treated copper foil in Examples andComparative Examples, the ten-spot average roughness of the surfacetreated surface was measured in accordance with JIS B 0601-1994 with acontact roughness meter Surfcorder SE-3C made by Kosaka Laboratory Ltd.The measurement was performed under the following conditions:measurement reference length: 0.8 mm; evaluation length: 4 mm; cutoffvalue: 0.25 mm; and feed rate: 0.1 mm/s. The measurement position of arolled copper foil was changed in the perpendicular direction (TD) tothe rolling direction, and the measurement position of an electrolytecopper foil was changed in the perpendicular direction (TD) to themovement direction of the electrolyte copper foil in the manufacturingdevice of the electrolyte copper foil, such that the measurement wasperformed 10 times, respectively. The value was obtained from the tentimes measurement.

The surface roughness (Rz) of the copper foil before surface treatmentwas also obtained in the same way, in advance.

(2) Measurement of Surface Color Difference ΔE*Ab

The measurement of the color difference ΔE*ab of the copper foil surfacefrom white color was performed in accordance with JIS Z 8730 with acolor difference meter MiniScan XE Plus made by HunterLab Inc. In themeasurement by the color difference meter, the measurement value of awhite plate is set to ΔE*ab=0, and the measurement value in the dark,covered with a black bag, is set to ΔE*ab=90, for the calibration of acolor difference. The ΔE*ab was measured based on the followingexpression, by using the L*a*b colorimetric system with ΔL: white andblack, Δa: red and green, and Δb: yellow and blue, wherein the colordifference ΔE*ab is defined as zero for white color and 90 for blackcolor.

ΔE*ab=√{square root over (ΔL ² +Δa ² +Δb ²)}  [Expression 2]

Measurement of surface color difference ΔE*ab was performed on thesurface treated surface of a surface treated copper foil.

The color difference ΔE*ab based on JIS Z 8730 of a microscopic regionsuch as the surface of a copper circuit may be measured with a knownmeasuring device such as a microscopic area spectroscopic colordifference meter made by Nippon Denshoku Industries Co., Ltd. (Model:VSS400 and the like) or a microscopic area spectroscopic colorimetermade by Suga Test Instruments Co., Ltd (Model: SC-50μ and the like).

(3) Surface area ratio of copper foil (A/B)

The surface area of a copper foil was measured with a laser microscope.The three-dimensional surface area A for an equivalent area B of 647μm×646 μm (417,953 μm² in actual data) of the surface treated surface ofa copper foil in each of Examples and Comparative Examples after surfacetreatment was measured with a laser microscope OLS4000 made by OlympusCorporation with a magnifying power of 20. The ratio was obtained by thefollowing expression: (three-dimensional surface areaA)÷(two-dimensional surface area B)=area ratio (A/B). Thethree-dimensional surface area A was measured with the laser microscopeat an environment temperature of 23 to 25° C.

(4) Glossiness

The measurement was performed with a gloss meter, Handy Gloss Meter PG-1made by Nippon Denshoku Industries Co., Ltd., in accordance with JIS Z8741. With regard to a rolled copper foil, the surface before surfacetreatment was measured in the perpendicular direction (TD) to therolling direction (movement direction of the copper foil during rolling,i.e., width direction) at an incident angle of 60 degrees. With regardto an electrolyte copper foil, the surface before surface treatment (matsurface) was measured in the perpendicular direction (i.e., widthdirection) (TD) to the transportation direction of the copper foilduring electrolytic treatment at an incident angle of 60 degrees.

(5) Gradient of Brightness Curve

The surface treated side of a manufactured copper foil was faced to apolyimide film so as to be laminated on both sides of the polyimide film(made by Kaneka Corporation, thickness: 25 μm or 50 μm (PIXEO for adouble layer copper clad laminate)). The whole of the copper foil on oneside was removed by etching. The copper foil on another side was etchedinto a linear form having a width of 0.3 mm. Subsequently, a sheet ofwhite paper was laid on the back face of the linear copper foil having awidth of 0.3 mm. The copper foil was photographed with a CCD camera (aline CCD camera with 8,192 pixels) through the polyimide film. Thebrightness of the photographed image was measured for the respectiveobservation spots along the direction perpendicular to the extendingdirection of the observed copper foil, so that an observation spotversus brightness graph was made. From the brightness curve extendingfrom an end of the mark to a portion without the mark, ΔB, t1, t2, andSv were measured. A schematic diagram illustrating the constitution of aphotographic device and a method for measuring the brightness curve foruse in the measurement are shown in FIG. 3. The polyimide having athickness of 25 μm or 50 μm for use in the evaluation of the gradient ofa brightness curve had a ΔB (Pl) of 50 or more and 65 or less beforebeing laminated to a copper foil. In measurement of ΔB (Pl) of thepolyimide before being laminated to the copper foil, a sheet of whitepaper printed with a black mark in a linear shape having a width of 0.3mm (a printed matter with a linear black mark) was used instead of acopper foil in a linear shape having a width of 0.3 mm.

The ΔB, t1, t2, and Sv were measured with the following photographingdevice. One pixel in the transverse axis corresponds to a length of 10μm.

A white gloss paper having a glossiness of 43.0±2 was used as the “whitepaper” laid on the “back face of a linear copper foil having a width of0.3 mm.”

A transparent film printed with various kinds of lines or the like asshown in FIG. 5 as dirt (made by Choyokai Co., Ltd., product name: “dirtmeasuring chart, full size version,” product number: JQA160-20151-1(made by National Printing Bureau, Independent Administrative Agency)),which is adopted in both of JIS P 8208 (1998) (FIG. 1: copy of dirtmeasuring chart) and JIS P 8145 (2011) (appendix JA (standard): dirtcomparison chart for visual observation method, and Figure JA. 1: copyof dirt comparison chart for visual observation method), was placed on asheet of white gloss paper having a glossiness of 43.0±2, for use as the“printed matter with a linear black mark”.

The glossiness of the gloss paper was measured with a gloss meter, HandyGloss Meter PG-1 made by Nippon Denshoku Industries Co., Ltd., inaccordance with JIS Z 8741 at an incident angle of 60 degrees.

The photographing device includes a CCD camera, a sheet of white paperon which a polyimide substrate laminated with a sample copper foil isplaced (the polyimide substrate laminated with a copper foil is placedsuch that the surface opposite to the surface having the linear copperfoil faces the CCD camera), a lighting power source which allows thephotographed part of the polyimide substrate to be irradiated withlight, and a transporting machine (not shown in drawing) whichtransports the copper foil and the polyimide substrate to bephotographed onto a stage. The main specifications of the photographingdevice are as follows:

Photographing device: sheet inspection device Mujiken made by NirecoCorporation;

Line CCD camera: 8,192 pixels (160 MHz), 1,024 gradation digital(10-bit);

Lighting power source: high frequency lighting source (power unit×2);and

Lighting: fluorescent lamp (30 W, model name: FPL27EX-D, twinfluorescent lamp).

A line drawn in the dirt in FIG. 5 indicated by arrow was used as theline for measuring ΔB (Pl), having 0.7 mm². The line has a width of 0.3mm. The viewing field of the line CCD camera was arranged as shown bydotted lines in FIG. 5.

In photographing by a line CCD camera, signals were confirmed in a fullscale with 256 gradations, and the lens aperture was adjusted such thatthe peak gradation signal of the spot where no black mark of a printedmatter is present is controlled to be within 230±5 (when the transparentfilm was placed on the white gloss paper such that the spot other thanthe printed mark on the dirt was measured with a CCD camera from thetransparent film side) in a state that no polyimide film (polyimidesubstrate) to be measured was placed. The scanning time of the camera(time period when the shutter of a camera is open, i.e., time period fortaking light in) was fixed at 250 μs, and the aperture of a lens wasadjusted to be within the gradations.

With regard to the brightness shown in FIG. 3, zero means “black,” and abrightness of 255 means “white.” The degree of gray color from “black”to “white” (density of black and white, i.e., gray scale) is thussegmented into 256 gradations for representation.

(6) Visibility (Transparency of Resin)

A copper foil was laminated on each of both sides of a polyimide film(made by Kaneka Corporation, thickness: 25 μm or 50 μm), and the copperfoil was removed by etching (ferric chloride aqueous solution) so as toform a sample film. A printed matter (a black circle with a diameter of6 cm) was attached to one surface of the produced resin layer, and thevisibility of the printed matter was determined through the resin layerfrom the opposite surface. In the evaluation, a sample having a clearcontour of the black circle for 90% or more of the circumference lengthwas ranked as “excellent,” a sample having a clear contour of the blackcircle for 80% or more and less than 90% of the circumference length wasranked “good” (the above were rated acceptable), and a sample having aclear contour of the black circle for 0 to less than 80% of thecircumference length or having a broken contour was ranked “poor”(unacceptable).

(7) Peel Strength (Adhesion Strength)

In accordance with IPC-TM-650, the normal peel strength was measuredwith a tension testing machine Autograph 100. A sample having a normalpeel strength of 0.7 N/mm or higher was determined to be applicable foruse in a laminated substrate. In the measurement of peel strength, thethickness of a copper foil was set to 18 μm. A copper foil having athickness less than 18 μm was copper plated to have a copper foilthickness of 18 μm. A copper foil having a thickness more than 18 μm wasetched to have a copper foil thickness of 18 μm. In measuring the peelstrength, a sample including a polyimide film made by Kaneka Corporationhaving a thickness described in Table 2 (25 μm or 50 μm) laminated on asurface treated surface of the surface treated copper foil according toExamples and Comparative Examples of the present application was used.The polyimide film was fixed by attaching to a hard base material (astainless steel plate or a synthetic resin plate (having no deformationduring measurement of peel strength)) with a double stick tape or aninstant adhesive for the measurement.

(8) Yield

A copper foil was laminated on each of both sides of a polyimide film(made by Kaneka Corporation, thickness: 50 μm), and the copper foil wasetched (ferric chloride aqueous solution) so as to form an FPC having acircuit width with an L/S of 30 μm/30 μm. Subsequently the detection ofa 20 μm×20 μm square mark was tried through polyimide with a CCD camera.A mark detectable 9 times or more out of 10 times was rated as“excellent,” a mark detectable 7 to 8 times was rated as “good,” a markdetectable 6 times was rated as “fair,” and a mark detectable 5 times orless was rated as “poor.”

The measurement of the items (1) to (3) of the copper circuit or thecopper foil surface of a print wiring board or a copper clad laminatemay be performed by dissolving and removing the resin.

The conditions and the evaluation of the respective tests are describedin Tables 1 to 3.

TABLE 1 Metal foil (before surface treatment) Roughness Glossiness TD TDType Process Thickness Rz (μm) (%) Example 1 Tough pitch copper Highgloss rolling, oil film equivalent 24,000  5 um 0.50 420 Example 2Oxygen free copper + Ag10 ppm High gloss rolling, oil film equivalent17,000 18 um 0.40 505 Example 3 Oxygen free copper + Sn70 ppm + B100 ppmHigh gloss rolling, oil film equivalent 17,000 70 um 0.40 505 Example 4Tough pitch copper + Zn200 ppm + High gloss rolling, oil film equivalent17,000 12 um 0.40 505 Ni200 ppm + Cr50 ppm Example 5 Oxygen freecopper + Sn2500 ppm High gloss rolling, oil film equivalent 17,000  9 um0.40 505 Example 6 Tough pitch copper + Ag180 ppm High gloss rolling,oil film equivalent 14,000 35 um 0.35 610 Example 7 Tough pitch copper +Ag180 ppm High gloss rolling, oil film equivalent 17,000 18 um 0.38 520Example 8 Electrolyte copper foil Electrolyte copper foil 18 um 0.55 520Example 9 Tough pitch copper High gloss rolling, oil film equivalent17,000 18 um 0.40 505 Comparative Tough pitch copper Normal rolling, oilfilm equivalent 25,000 18 um 0.70 192 Example 1 Comparative Tough pitchcopper High gloss rolling, oil film equivalent 17,000 18 um 0.40 505Example 2 Comparative Tough pitch copper High gloss rolling, oil filmequivalent 17,000 18 um 0.40 505 Example 3 Comparative Tough pitchcopper + Ag 180 pm High gloss rolling, oil film equivalent 17,000 18 um0.38 520 Example 4

TABLE 2 Surface treatment ΔE*ab Plating Current Roughness Surface(copper Resin Peel bath density Plating TD area ratio foil thicknessstrength (Table 3) (A/dm²) time (sec) Rz (μm) A/B surface) (μm) ΔB Sv(N/mm) Visibility Yield Example 1 (1) 43 1 0.54 1.56 52 50 55 3.0 1.50 ◯Δ Example 2 (1) 35 1 0.35 1.25 40 50 40 3.5 0.74 ◯ ◯ Example 3 (1) 37 10.42 1.35 43 50 55 4.7 1.35 ⊚ ⊚ Example 4 (1) 40 1 0.46 1.43 53 50 525.2 1.45 ⊚ ⊚ Example 5 (1) 45 1 0.47 1.68 57 50 55 6.0 1.55 ⊚ ⊚ Example6 (1) 45 1 0.42 1.44 57 25 63 6.4 1.45 ⊚ ⊚ Example 7 (2) 35 1.3 0.531.20 62 50 45 3.7 1.70 ⊚ ⊚ Example 8 (2) 30 0.8 0.58 1.51 59 25 55 4.01.8 ⊚ ⊚ Example 9 (3) 2 20 0.50 1.53 63 50 42 3.8 1.10 ⊚ ⊚ Comparative(1) 35 2 0.78 1.78 64 25 37 2.5 1.4 X X Example 1 Comparative (1) 35 0.50.41 1.17 38 50 43 3.3 0.65 X X Example 2 Comparative (4) 1 2 0.40 1.1025 50 55 2.9 0.74 X X Example 3 Comparative (5) 55 1 1.00 1.80 50 25 251.4 1.80 X X Example 4

TABLE 3 Plating bath (1) Plating bath (2) Plating bath (3) Plating bath(4) Plating bath (5) Cu 15 g/L Cu 20 g/L Ni 25 g/L Zn 10 g/L Cu 10 g/LCo 8.5 g/L Ni 5 g/L W 20 mg/L Ni 10 g/L H₂SO₄ 50 g/L Ni 8.6 g/L P 1 g/LpH 3.6 pH 3.6 Bath temperature pH 2.5 pH 2.0 Bath temperature Bathtemperature 25° C. Bath temperature Bath temperature 40° C. 40° C. 38°C. 30° C.

(Evaluation Results)

In Examples 1 to 9, any one of the samples had a color difference ΔE*abof the copper foil surface of 40 or more, and a ΔB of 40 or more, sothat the visibility was excellent.

In Comparative Examples 1 to 4, the samples had a color difference ΔE*abof the copper foil surface of less than 40, or a ΔB of less than 40, sothat the visibility was poor.

The SEM observation photographs of the copper foil surface inComparative Example 1 and Example 1 for the evaluation of Rz are shownin FIGS. 4 (a) and 4 (b), respectively.

In Examples 1 to 9, the width of the linear copper foil mark having awidth of 0.3 mm and the width of the dirt mark were changed from 0.3 mmto 0.16 mm (for dirt, a mark arranged thirdly closer to the description0.5 having an area of 0.5 mm² in the sheet of dirt (mark indicated byarrow in FIG. 6)) for the same measurement of ΔB (Pl), Sv value, and ΔBvalue. As a result, the same values as for the mark having a width of0.3 mm were obtained in any of the ΔB (Pl), Sv value, and ΔB value.

Furthermore, in Examples 1 to 9, the “top average Bt of brightnesscurve” representing the average of brightness measured at 5 spots atintervals of 30 μm from a position 50 μm away from the end position ofboth sides of the mark (total 10 spots on both sides) was changed to theaverage of brightness measured at 5 spots at intervals of 30 μm from aposition 100 μm away, from a position 300 μm away, and from a position500 μm away, from the end position of both sides of the mark (total 10spots on both sides), respectively for the same measurement of ΔB (Pl),Sv value, and ΔB value. As a result, the same values as for the “topaverage Bt of brightness curve” representing the average of brightnessmeasured at 5 spots at intervals of 30 μm from a position 50 μm awayfrom the end position of both sides of the mark (total 10 spots on bothsides) were obtained in any of the ΔB (Pl), Sv value, and ΔB value.

1. A surface treated copper foil comprising: at least one surfacetreated surface with a color difference ΔE*ab of 40 or more based on JISZ 8730, and a difference between a top average Bt and a bottom averageBb in a brightness curve extending from an edge of the copper foil to aportion without the copper foil ΔB (ΔB=Bt−Bb) of 40 or more, afterlamination of the surface treated surface to a polyimide having a ΔB(Pl) defined as above of 50 or more and 65 or less before beinglaminated to the copper foil, wherein the brightness curve is obtainedfrom an observation spot versus brightness graph of measurement resultsof the brightness of a photographed image of the copper foil through thepolyimide with a CCD camera for the respective observation spots alongthe direction perpendicular to the extending direction of the observedcopper foil.
 2. The surface treated copper foil according to claim 1,further comprising: an Sv defined by the following expression (1) of 3.0or more:Sv=(ΔB×0.1)/(t1−t2)  (1); wherein t1 represents a value pointing theposition of the intersection closest to the copper foil among theintersections of the brightness curve and Bt in the observation spotversus brightness graph, and t2 represents a value pointing the positionof the intersection closest to the copper foil among the intersectionsof the brightness curve and 0.1ΔB in the range from the intersections ofthe brightness curve and Bt to a depth of 0.1ΔB with Bt as reference. 3.The surface treated copper foil according to claim 1, wherein thesurface of the surface treated copper foil has a color difference ΔE*abof 43 or more.
 4. The surface treated copper foil according to claim 3,wherein the Sv defined by the expression (1) in the brightness curve is3.5 or more.
 5. (canceled)
 6. (canceled)
 7. The surface treated copperfoil according to claim 1, wherein the surface has a TD averageroughness Rz of 0.20 μm to 0.64 μm, and the copper foil surface has athree-dimensional surface area A to two-dimensional surface area B ratioA/B of 1.0 to 1.7.
 8. (canceled)
 9. (canceled)
 10. A laminate comprisinga lamination of the surface treated copper foil according to claim 1 anda resin substrate.
 11. A printed wiring board comprising the surfacetreated copper foil according to claim
 1. 12. An electronic apparatuscomprising the printed wiring board according to claim
 11. 13.(canceled)
 14. A method for manufacturing a printed wiring board havingtwo or more connected printed wiring boards comprising connecting atleast one printed wiring board according to claim 11 to another printedwiring board according to claim 11 or to a printed wiring board otherthan the printed wiring board according to claim
 11. 15. An electronicapparatus comprising at least two printed wiring boards connected toeach other manufactured according to the method of claim
 14. 16. Amethod for manufacturing a printed wiring board comprising connecting aprinted wiring board according to claim 11 and a component.
 17. A methodfor manufacturing a printed wiring board having two or more connectedprinted wiring boards comprising: connecting at least one printed wiringboard according to claim 11 to another printed wiring board according toclaim 11 or to a printed wiring board other than the printed wiringboard according to claim 11, and connecting a printed wiring boardaccording to claim 11 to a component.
 18. The surface treated copperfoil according to claim 2, wherein the surface of the surface treatedcopper foil has a color difference ΔE*ab of 43 or more.
 19. A laminatecomprising the surface treated copper foil according to claim 2 and aresin substrate.
 20. A printed wiring board comprising the surfacetreated copper foil according to claim
 2. 21. An electronic apparatuscomprising the printed wiring board according to claim
 20. 22. A methodfor manufacturing a printed wiring board having two or more connectedprinted wiring boards comprising: connecting at least one printed wiringboard according to claim 11 to another printed wiring board according toclaim 11 or to a printed wiring board other than the printed wiringboard according to claim 11, and connecting a printed wiring boardhaving two or more connected printed wiring boards to a component, theprinted wiring board having two or more connected printed wiring boardsbeing manufactured by a method comprising connecting at least oneprinted wiring board according to claim 11 to another printed wiringboard according to claim 11 or to a printed wiring board other than theprinted wiring board according to claim 11.